Die casting apparatus



Jan. 18, 1938. J. R. DAESEN ET AL 2,105,586

DIE CASTING APPARATUS Filed July 13, 1936 282m r v5 y? i 2a V40 types.

Patented Jan. 18, 19,38

WED.. STATES, 'PATENT poFFicE DIE lCASTING APPARATUS I John R. Daesen,OakPark, and

' ple, Chicago, YIll.

Lela-.1a E. wem

Application '.Iuly 13, 1936, Serial No. 90,430

N v 1s claims. VOur invention relates. to-an apparatus for die castingmetals and other substances and more l and apparatus for die sion couldbe greatly reduced by adding aluminum to the zinc, this, however, led toan, unstable alloy which failed because of intercrystalline oxidationand corrosion. Great improvements in the stability of `the zinc aluminumalloy have been made by regulating the natural impurities and makingvarious additions to the alloy without,

however, securing a completely stable alloy.

In order to die cast zinc alloys not containing aluminum, and whichalloys would therefore corrodethe parts of the die casting machinecoming in contact therewith,` die casting machines have been constructedwhich avoided continuous contact between the molten metal and themetallic parts of the machine. This has been accomplished by providing amelting chamber separate from the machine and ladling an amount o fmetal sumcient for one charge or casting into a cavity in a mold. Asolid plunger operating in the cavity is usuallyemployed to compress themolten or pasty metal into the mold cavity. While such machines. in adegree avoided the corrosion causedby aluminum-free zinc, and brass andaluminum, they possessed the disadvantage that they were fed manuallyand were thus limited to .operating speeds considerably less than theearlier An alternate method of avoiding corrosionA of the die castingmachine by the moltemmetal is illustrated and described in our priorPatent No.

' e1,999,981. Because of 'its construction, -it possesses onedisadvantage, namely, that the amount of pressure which can' be exertedis limited. Inasmuch' as its operation is automatic and does not requiremanual feeding, it is free fromithe objection of slow speed oftherefore, a useful method especially in its corrosive preventingfeature.

Our present invention, although it can, as will be seen, be used togreat advantage in connection with other methods and apparatus, isAimpecially designed .as an improvement for use with the operation andit is,-

invention disclosed in our Patent No. 1,999,961. When so employed itmakes possible an automatic high speed production of castings,particularly zinc alloy castings molded under very high pressures.'I'his is the principal object ofthe in- 5 vention.

According tb our invention, the molten material is passed from acrucible or reservoir through a duct into a cylinderand thence through agate or passageway on one side of the cylinder into the 10y mold cavity.A plunger operating in the cylinder has an extension or stud on its endwhich closes the duct after a suilicient quantity of metal has beendrawn into the cylinder. 'I'he plunger then continuing its downwardmovement, compresses 15 the metall through the gate or passageway and yinto the mold cavity with as much pressure as is desired since becauseof its construction, the plunger and cylinder can be built strong enoughto resist tremendous pressures. 'Ihe stud extend 20 ing from the plungerbesides closing the duct and preventing the molten metal from runningback into the crucible, operates as it continues its downward movementto pinch oi and eject the solidied metal left in the duct ahead of thecyl- 25 inder causing the same to drop back into the crucible. Thisaction fis ofv advantage particularly in connection with the methoddisclosed in our Patent No.- 1,999,961 where the duct is kept at arelatively low temperature. 30

It will be noted that one single downward stroke of the plunger and studeects three es- ;sential steps; rst, closing the duct; second,compressing the molten metal into the mold cavity; and third, ejectingthe solidified metal in that 35 part ofthe duct leading to the cylinder.All three steps are accomplished quickly and'simply.

So that the nature of invention shall be per- -fectly clear anarrangement by which it may be carried out has been illustrated in theaccompanying drawing in which the single ligure is a. vertical sectionof a die casting machine embodying the invention. Referring specificallyto the arrangement illustrated, the metal 2 to be melted and cast is 45placed in a graphite crucible 4 which may be heated by any suitablemeans, such as through a'l salt bath 8, by electrical resistanceelements A 8. These elements may be embedded in the inner wall III ot apressure tight chamber I2. The inner 5o wall of the chamber ispreferably insulated from the outer wall by means of suitable insulatingmaterial I4. Obviously, the metal may be melted in other ways. l

'I'he cover IB o! the pressure tight chamber I2 55 is provided with anopening I8 for the insertion of the duct 20. Depending from the underside of the cover around the edge of the opening is a ceramic ring 22.This is for the purpose of keeping the salt bath 6 clear from the ,metalsurface beneath the duct opening.

The cover I6 is also provided with an enlarged portion 24 having acylindrical bore therein through which slides a pressure operated piston26 supplied with power from any suitable source as from the hydraulic orcompressed air cylinder I.

The uprights 28 support the cover I6 which is held securely in place onthe chamber I2 by means of the nuts 38 and lock nuts 32. The uprigh'ts28 extend upwardly above the cover I6 but these extended portions are oflesser diameter than the portions which support the cover I6 so that thenuts 38 and 32 can be loosened thus permitting the cover I6 to be raisedand the crucible 4 'to be reillled or replaced. The upper extensions ofthe uprights 28 rigidlysupport a plate 34 to which the cylinder I issecured.

The plate 34 supports a compressed air or hydraulic cylinder II providedwith a piston 36 which is connected by the rod 38 to a plate 48, asuitable opening being provided in the plate 34 to enable the rod 38 topass therethrough.

The die 42 is disposed in a recess inthe cylinder member 44. The die andcylinder member are preferably made up of upper and lower halves.

The cylinder member is provided with a cylindrical space 46 and thisspace is connected to the duct 28 by the opening 48. .The cylindricalspace 46 is connected to the mold cavity in the die 42 by means of agate or passageway 58.

A pressure piston 52 is disposed in the cylindrical space 46. Thispiston is adapted to. be

moved up or down by any suitable means such as by the hydraulic or ac ircylinder III. The piston 52 is provided at its lower end with a. stud 54which is so disposed as to enter and close off the opening 48 tothe duct28 when the piston 52 is moved downwardly. The stud 54 is dimensioned,however, so as to permit the piston 52 to move downwardly for somedistance even after the duct opening 48 has been closed.

The die and the cylinder member are preferably split Ahorizontall linder member 44 is connected rigidly wlththe plate 48 by meansoof therods 56. These rods `pass through suitable openings in the upper half ofthe cylinder member so that the upperv half can be raised and loweredvertically while being guldedby these rods. This raising and lowering lof the upper half of the cylinder member may be accomplished by thecompressed air or hydraulic cylinder IV connected to the plate 40 andwhich is provided with the piston 58 secured to the upper half of thecylinder member.

The operation of the arrangement will'be described in connection withthe casting of zinc alloys or other metals. The zinc or other metal tobe cast is placed in the cruclble and melted through the salt bath 6 byheat from the' resistance elements 8. The salt bath extends overv themolten zinc in the crucible 4 except for that portion of the latterwhich is directly below the duct opening I8. This excepted portion iskept clear by reason of the 'ceramic ring 22 which depends from thechamber cover I6 extending down below the uppersurface of the moltenuzinc or l other material in theA crucible.

The die and cylinder member as a unit are The lower half of the cylcharge or shot has entered the space 46, the piston I 52 which moves inthis space is moved downwardly by operation of the cylinder III so thatthe stud 54 thereon closes the opening 48. Instead of having the pistonand stud integral the piston may be provided with a vertical bore toreceive a separately operated stud capable of moving up and downtherein.

The piston then continues its downward movement and as it does so itpinches off and ejects from the opening 48 any metal which hassolidifled therein. This ejected metal falls back into the crucible. Theopening 48 is thus kept clean at all times. Simultaneously the downward,movement of the piston 52 causes pressure in any desired amount to beapplied to the molten or plastic metal in the space 46 to force asuicient amount of such metal through the gate or passageway 58 into themold cavity in the die 42 to fill the mold cavity completely. The twohalves of the cylinder member and die are during this time held tightlytogether by means of pressurev within the cylinder IV.

In order to avoid compressing a considerable volume of air in making ashot, the salt bath in the chamber I2 should completely i'lll thesurface in the chamber with the exception, of course,

' of the area thereof within the ceramic ring 22.

We have foundI that a pressure of 500 lbs. per square inch in thepressure chamber may be used to force the molten metal into the ldie byway of the space inthe cylinder member. After the duct has been closedby the stud 54 it is possible to compress the metal in the space in thecylinder member and consequently in the mold' molten metal in thecruclble as soon as a suilicient amount of metal has passed to the spacein the cylinder member and as soon as the stud has closed the opening 48to the duct. This is accomplished by raising the cylinder member and dieas a unit by operation of the cylinder II and piston 36. 'I'his will aidconsiderably in avoiding or lessening corrosion of the duct. Moreover,the duct can advantageously be kept at a ternperature enough lower thanthe melting point of the metal to freeze the contacting layer of moltenmetal rapidly before corrosive action takes place between it and theduct. This feature is described and claimed in our prior Patent No.1,999,961.

Where, of course, the metal being cast is not corrosive, or where it ispossible to protect the nose of the duct from corrosion by other means,lt will not be necessary to break the contact between the molten metaland the duct immediately after the space 46 has been lled with enoughmetal for one charge. the case the duct and lower half of the cylinderWhere such is member and die may be secured so as to remain 75 Thus alsowhere they material. being molded is' a plastic such asa phenoliccondensation product or the like, it is not necess'yto. raise the ducteach, time after the space in the cylinder member has been provided witha charge since such plastics do notiexert a corrosive inuence on theduct. `V ,A

After the casting operation has been completed in an arrangement such asillustrated, the die and cylinder member may be split vby operation ofcylinderIV and upward movement-of the piston 58, one of the realadvantages of the invention being that it is capable of use forautomatic high pressure rapid voperating die casting of various metals,alloys, plastics, and particularly of zinc, zinc alloys, and the like.When the die is opened the casting in the mold cavity and gate andsurplus inthe cylinder member may be removed in one piece.- This howevermay also be effected in an arrangement in which the die splitsvertically.

` It will be noted that a single downward/movement of the piston 52eifects three important steps. First, it closes the opening to the duct;

secondly, it ejects the metal which has solidiiiedA in the duct opening,and; thirdly, it'applie's a very great pressure. to the molten metal asit 'forces the same into the mold cavity. This construction is bothsimple and eective as .well'as l extremely adaptable for high speed,high pressure castings in which all the steps are automatic. Naturally,changesin the apparatus may be made which do not aect the real natureof-'the invention and we do. not intend to be limited by the exemplarydisclosure herein except within the scope of the appended claims.

Having now described our invention what we claim as new and wish toprotect by Letters Patent of the United States is:

l. In a die casting machine, a ember having a space therein forreceiving molten metal, a duct throughgwhich molten metal may pass tosaid space, means for momentarily contacting a portion of said ductwith`a source of molten metal and for forcing a quantity of said `metalunder hydrostatic pressure into said space during the momentary periodofx contact, a mold, a passage between saidspace and said mold, and

means movable in said space to close said duct and to force molten metalin said space through said passage `and into said mold vunder pressure.

2. In a die casting machine, a chamber for receiving molten material, acasting apparatus in non-continuous contact with said chamber, saidapparatus comprising a member having a space therein for receivingmolten metal, a duct through which molten metal' maypass to said spaceunder hydrostatic pressure, a mold, a passage between-said space andsaid mold, and a single means movable in said space, said, means during`the rst part of its movement closing the entrance to said duct andthereafter applying pressure to molten metal within. said space tofofrce'` the same through said passage into said lrnold, said means alsoacting to shear from the entrance lto the duct any metalwhich may havesolidified therein. I

3. In a die casting machine, a chamber for receiving' molten material,va casting apparatus in non-continuous contact `with said chamber,`

said apparatus comprising a member provided with a cylinder, a ductleading to said cylinder from below to permit molten metal to pass intosaid cylinder, a mold, a passage connecting said mold, and the lowerportion of said cylinder, a piston movable up and down in said cylinder,

lsaid piston having a stud extension on its lower end for closing saidduct, and means to move said piston downwardlyiirst to close said duct,

' and secondly on continued downward movement ing said die unit so thatsaid duct contacts momentarily with the molten metal in said crucible, 4

means for forcing the xmolten metal under pressure through said duct andinto said cylinder during kthe brief period of contact between the ductand the molten metal, a piston movable in said cylinder, -a studextending from the lower end of said piston, means for moving saidpiston downwardly as soon as a chargeof metal has entered said cylinderto close the entrance to the same and before the contact between ductand metal is broken, further actuation of said means and consequentdownward movement of said piston acting to pinch off and eject from theopening in said duct any metal which has solidiiied therein and to forcethe molten metal through the passageway and into the mold cavity undergreat pressure.

5. An apparatus as claimed in claim 4,1" and means for automaticallysplitting said mold and cylinder as soon as the casting has beencompleted so that the molded article, the metal in the passageway andinthe cylinder may be rezinc base alloys and the like, which consists ofa crucible for molten metal, a die ,unit consisting of a mold, acylinder connected to said mold, a passageway between them, and a ductleading to said cylinder from below, said die unit being splithorizontally into upper and lower halves, hydraulic means for loweringsaid die unit so that a small portion of said duct contacts momentarilywith the molten metal in said crucible and for then raising said dieunit, hydraulic means for forcing the molten metal under pressurethrough said duct and into said cylinder during the brief period ofcontact between the duct and the molten metal, a piston movable in saidcylinder, a stud extending from the lower end of said piston, hydraulicmeans for moving said piston downwardly as soon as a charge of metal hasen` tered said cylinder to close the entrance of the same and beforecontact between duct and metal is broken, further actuation of saidlmeans and consequent movement of said piston acting to pinch oil andeject from the opening in said duct any metal which has solidied thereinand to force the molten ymetal through the passageway and into the moldcavity under great pressure,

and hydraulic means for automatically splitting said mold and cylinderhorizontally to separate the same as soon as the casting has beencompleted and so that the molten article, the metal in the passagewayand in the cylinder may be removed in one piece.

7. A method of die casting zinc alloys and the like which comprisesmomentarily submerging the inlet end o! a duct of'a die in a source ofmolten metal, forcing by hydrostatic pressure a quantity of said moltenmetal through said duct and into a space adjacent the die cavity whilethe contact between the duct and molten metal exists, simultaneouslyclosing the duct opening,

breaking the contact, and forcing the molten metal in said space intothe die cavity.

8. A method as dened in claim 7 in which the .end of said duct meanswith said aperture, means to force molten material from said chamberinto said duct means, and means within said duct means to close thepassageway of said duct means to said chamber and to force the moltenmaterial in saidduct means into said die.

10. In a die casting machine, a source of molten material, a diesupporting member spaced from said source of material, a die supportedupon said member, a passageway extending from said die to a pistonspace, a duct extendingl from said space to an opening in said member,piston means in said space, means to bring said duct in contact withsaid source of material, means to ll said space through said duct withmolten material, means to operate said piston to close said duct whilemaintaining said contact and to force said material in said space intosaid die, and means to separate said duct from said sourceof material.

11. In a die casting machine as in claim 10,

said piston meansl comprising a piston and a stud on said piston, saidstud being adapted to close said duct while said piston forces saidmaterial into said mold,` whereby said duct is freed of frozen material.

12. In a die casting machine 'as in claim 10, said source of materialcomprising a chamber,

an aperture in a wall of said chamber, said duct engagingsaid apertureto make an airtight joint.

13.-\ In a. die casting machine as in claim 10, said source of materialcomprising a chamber, an aperture in a wall of said chamber, said ductengaging said aperture, and hydrostatic means in said chamber adakitedto force said molten materia1 through said duct into said space.

14. In a die casting machine, a chamber for holding molten material,heating means for 'said chamber, a crucible within said chamber, saidCrucible containing said material, a heating bath surrounding saidcrucible, a top wall for said chamber, an aperture in said wall abovesaid crucible, a ceramic ring depending from said wall into saidcrucible, said ring extending around said aperture whereby said bath isprevented from passing through said aperture, and plunger means in saidbath adapted when operated to force molten material under hydrostaticpressure through said aperture.

15. :In a die casting apparatus a source of molten material, a diecasting member, andvmeans `moving said member into intermittent contactwith said source of material, said member comprising a receiving chamberfor said material communicating with said source, a mold incommunication with said chamber, and a single movable means in saidchamber closing communication between said chamber and said source whilesaid member contacts said source and forcing material 'in said chamberinto said mold while said member is out of contact with said source.

` JOHN R. DAESEN.

LELAND E. WEMPLE.

